CN114337205B - Common-mode peak suppression method for robot servo driver IMC - Google Patents

Abstract

The application provides a common-mode peak suppression method of a robot servo driver IMC, which comprises the following steps: dividing the input voltage of the rectifier stage into 6 rectifier stage sectors according to phase angles; in each rectification stage sector, a reference current vector is obtained by synthesizing two adjacent effective current vectors; dividing the output voltage of the inverter stage into 6 inverter stage sectors through 6 effective voltage vectors; respectively calculating the magnitude of common-mode voltage under the action of the effective current vector of the rectifying-stage sector in which the current reference current vector falls and 6 effective voltage vectors; selecting 3 effective voltage vectors corresponding to small common-mode voltageV _α、V _β、V _γSynthesizing a reference output voltage vector; adjusting the effective voltage vector according to the three-phase current direction of the inversion stage sector where the current reference output voltage vector is locatedV _α、V _β、V _γAnd switching the sequence. The method provided by the application can restrain the common-mode voltage to 29%, and eliminates common-mode voltage spikes generated by dead zone effects.

Description

Common-mode peak suppression method for robot servo driver IMC

Technical Field

The disclosure relates generally to the technical field of indirect matrix converters, and in particular to a common-mode peak suppression method for an IMC (inertial measurement unit) of a robot servo driver.

Background

The servo driving system is one of the key parts of the robot, and the reliability of the servo driving system directly influences whether the robot can normally complete the work task. An Indirect Matrix Converter (IMC) as a new ac-ac converter has advantages of sinusoidal input and output current, controllable power factor, no intermediate energy storage link, and bidirectional energy flow, and becomes a new generation of robot servo driver with wide application prospects.

The indirect matrix converter can generate high-frequency and high-amplitude common-mode voltage (CMV) at a neutral point of an output end load in The operation process, and when The servo motor is driven, The high-frequency and high-amplitude common-mode voltage can excite a coupling capacitor of a motor system to generate shaft current, so that The bearing is damaged, The motor winding fails, and The service life of The servo motor is greatly shortened. Due to high switching frequency, common mode voltage can also generate leakage current flowing through a winding in stray capacitance of the motor, the leakage current can cause misoperation of a motor protection circuit, insulation of the motor is seriously damaged, strong electromagnetic interference can be generated, and normal operation of other electronic equipment is influenced.

The indirect matrix converter is used as a robot servo driver, and the common-mode voltage generated on the output side of the indirect matrix converter causes great harm to a motor system, so that the reliability of the whole robot servo system is seriously influenced. The shaft current of the motor can be reduced, the torque ripple can be reduced by inhibiting the output common mode voltage of the IMC, the running reliability of a motor system is improved, the service life of the motor is prolonged, the reliability of the whole robot servo system is further improved, and the normal operation of the robot is ensured.

At present, the suppression methods for the common-mode voltage of the indirect matrix converter are mainly divided into two categories, namely hardware and software, and the hardware method mainly uses an output filter or improves a topological structure, so that the common-mode voltage can be effectively suppressed, but the weight, the volume, the loss and the cost of a system are increased to different degrees. In contrast, a software approach by optimizing the modulation strategy is more attractive, does not change the original structural features of the indirect matrix converter, and is easier to implement. The existing rejection about the common-mode voltage of the indirect matrix converter is mainly realized by avoiding using a zero vector or reasonably placing the position of the zero vector to reject the common-mode voltage when the zero vector is used, and the rejection can only reject 42% of the peak value of the common-mode voltage.

Disclosure of Invention

In view of the above-mentioned drawbacks and deficiencies of the prior art, it is desirable to provide a method for common mode peak suppression of a robot servo driver IMC that solves the above-mentioned technical problems.

The application provides a common-mode peak suppression method of a robot servo driver-IMC, which comprises the following steps:

dividing the input voltage of the rectifier stage into 6 rectifier stage sectors according to phase angles; each said rectifier stage sector including a maximum input phase voltage peak, a minimum input phase voltage peak, a maximum input line voltage peak, and a minimum input line voltage peak; within each said rectifier stage sector, a reference current vector I_refFrom two adjacent effective current vectors I_m、I_nSynthesizing to obtain;

dividing the output voltage of the inverter stage into 6 inverter stage sectors through 6 effective voltage vectors, wherein the three-phase current direction of each inverter stage sector is not changed;

respectively calculating the current reference current vector I_refThe magnitude of the common-mode voltage under the action of the effective current vector of the falling rectifying-stage sector and 6 effective voltage vectors;

selecting 3 effective voltage vectors V corresponding to small common-mode voltage_α、V_β、V_γSynthesizing a reference output voltage vector V_ref；

According to the current reference output voltage vector V_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γSwitching order to minimize a common mode voltage corresponding to an equivalent voltage vector of the switching process within the dead time;

according to the current reference output voltage vector V_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γThe method for switching the sequence specifically comprises the following steps:

obtaining a current reference output voltage vector V_refThe three-phase current direction of the sector of the inverter stage is located;

acquiring the corresponding switch states of two effective voltage vectors in each switching subsequence, calculating the switch state of an equivalent voltage vector based on the three-phase current direction, and acquiring the equivalent voltage vector corresponding to the equivalent voltage vector based on the switch state of an equivalent switching tube; the switching subsequence is the effective voltage vector V_α、V_β、V_γThe switching sequence of two adjacent effective voltage vectors in the dead time;

obtaining a current reference current vector I_refCalculating the effective current vector of the sector of the rectification stage, and calculating the equivalent common-mode voltage of the effective current vector and each equivalent voltage vector;

obtaining a current reference current vector I_refMinimum input line voltage peak value of the sector of the rectification stage;

selecting a switching subsequence corresponding to the minimum input line voltage peak value 1/3 in all equivalent common mode voltage peak values to obtain the effective voltage vector V_α、V_β、V_γAnd switching the sequence.

According to the technical scheme provided by the embodiment of the application, two adjacent effective current vectors I_m、I_nSynthesizing the reference current vector I by a formula (I) and a formula (II)_ref：

I_ref＝(d_{α_m}+d_{β_m}+d_{γ_m})I_m+(d_{α_n}+d_{β_n}+d_{γ_n})I_n(one);

wherein d is_αIs an effective voltage vector V_αDuty cycle of (d); d_βIs an effective voltage vector V_βDuty cycle of (d); d_γIs an effective voltage vector V_γDuty cycle of (d); d_mAs the effective current vector I_mDuty cycle of (d); d_nAs the effective current vector I_nThe duty cycle of (c).

According to the technical scheme provided by the embodiment of the application, d is calculated according to a formula (three) and a formula (four)_α、d_β、d_γ、d_m、d_nThe value of (c):

wherein, theta₁Is shown as I_refAnd I_mThe included angle of (A); theta₂Is a V_refAnd V_αThe included angle of (A); u. of_DCThe average value of the direct current bus voltage in one carrier period is obtained; u. of_{DC_m}And u_{DC_n}Are respectively d_mAnd d_nThe dc bus voltage when active.

According to the technical scheme provided by the embodiment of the application, the reference output voltage vector V is synthesized according to a formula (V)_ref：

V_ref＝(d_{α_m}+d_{α_n})V_α+(d_{β_m}+d_{β_n})V_β+(d_{γ_m}+d_{γ_n})V_γ(V).

According to the technical scheme provided by the embodiment of the application, the 6 effective voltage vectors comprise 3 odd effective voltage vectors and 3 even effective voltage vectors;

the included angle between two adjacent effective voltage vectors is 60 degrees, and the odd effective voltage vectors and the even effective voltage vectors are arranged at intervals;

two adjacent effective current vectors I_m、I_nIs 60 degrees.

According to the technical scheme provided by the embodiment of the application, the method further comprises the following steps:

according to the effective current vector I of the current input voltage in the rectifying stage sector_m、I_nControlling a switching state of the IMC rectification stage;

controlling a switching state of the IMC inverter stage to adjust the effective voltage vector V_α、V_β、V_γAnd switching the sequence.

The beneficial effect of this application lies in: the current reference current vector I is respectively calculated by dividing the input voltage of the rectifier stage into 6 rectifier stage sectors according to the phase angle, dividing the output voltage of the inverter stage into 6 inverter stage sectors through 6 effective voltage vectors_refThe effective current vector of the falling rectifying stage sector and the common-mode voltage under the action of 6 effective voltage vectors are selected, and 3 effective voltage vectors V corresponding to small common-mode voltage are selected_α、V_β、V_γSynthesizing a reference output voltage vector V_refSo that the common mode voltage peak can be suppressed to 0.29V_in；

Because the three-phase current directions of each sector of the IMC inverter stage are different, when the effective voltage vector switching of the inverter stage needs two switching tubes to act simultaneously, other vectors are inevitably introduced due to the action of a freewheeling diode in dead time, so that the common-mode voltage peak value of the inverter stage is increased, and the dead time effect is realized. The common mode voltage spike caused by the dead zone effect may seriously affect the peak suppression effect of the common mode voltage. By outputting a voltage vector V in accordance with the present reference_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γSwitching order and deathThe common-mode voltage peak value corresponding to the equivalent voltage vector in the switching process in the time is minimum, so that the common-mode voltage peak value caused by the dead zone effect can be eliminated, and the common-mode voltage peak value of the indirect matrix converter is restrained by 71%.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

fig. 1 is a flowchart of a common mode peak suppression method of a robot servo driver IMC according to the present disclosure;

FIG. 2 is a schematic of a topology of an indirect matrix converter;

FIG. 3 is a schematic diagram of the spatial arrangement of rectification stage effective current vectors and inversion stage effective voltage vectors of the indirect matrix converter shown in FIG. 1;

FIG. 4 is a schematic diagram of the three-phase input phase voltage of the present application dividing the input voltage into 6 sectors;

FIG. 5 is a schematic diagram of a three-phase input line voltage with an input voltage divided into 6 sectors according to the present application;

FIG. 6 is a schematic diagram of the present application dividing the output voltage into 6 sectors and the three-phase current direction of each sector;

FIG. 7 shows a schematic view of the present application from V₁To V₃A switching state equivalent schematic diagram in dead time in the switching process;

FIG. 8 shows a reference current vector I for the first sector of the rectifier stage_refAnd a reference voltage vector V of a first sector of the inverter stage_refA schematic diagram;

FIG. 9 shows a reference current vector I for the second sector of the rectifier stage_refAnd inverting stage first sector reference voltage vector V_refA schematic diagram;

fig. 10 is an experimental waveform diagram under the conventional SVM method and at the voltage transfer ratio m equal to 0.2;

fig. 11 is an experimental waveform diagram when the voltage transfer ratio m is 0.2 using the method of the present application;

fig. 12 is a waveform diagram of an experiment using the conventional SVM method and having a voltage transfer ratio of m 0.4;

fig. 13 is an experimental waveform diagram when the voltage transfer ratio m is 0.4 by the method of the present application.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

Please refer to fig. 1, which is a method for suppressing a common mode peak of a robot servo driver IMC provided by the present application, including the following steps:

s100: dividing the input voltage of the rectifier stage into 6 rectifier stage sectors according to phase angles; each said rectifier stage sector including a maximum input phase voltage peak, a minimum input phase voltage peak, a maximum input line voltage peak, and a minimum input line voltage peak; within each said rectifier stage sector, a reference current vector I_refFrom two adjacent effective current vectors I_m、I_nSynthesizing to obtain;

specifically, as shown in fig. 4 and 5, the input voltage of the rectification stage is divided into 6 sectors of the rectification stage, namely a first sector of the rectification stage and a sixth sector of the rectification stage, by 6 reference current vectors on average; with maximum peak input phase voltage V in each rectifier stage sector_inMinimum input phase voltage peak value V_in/2, maximum input line voltage peak

Minimum input line voltage spike

。

In the present embodiment, taking the input voltage of the rectifier stage as shown in fig. 4 and 5 as an example, it is possible to use-pi/6 to pi/6 of the input voltage of the rectifier stage as the first sector of the rectifier stage, pi/6 to pi/2 as the second sector of the rectifier stage, pi/2 to 5 pi/6 as the third sector of the rectifier stage, 5 pi/6 to 7 pi/6 as the fourth sector of the rectifier stage, 7 pi/6 to 3 pi/2 as the fifth sector of the rectifier stage, and 3 pi/2 to 11 pi/6 as the sixth sector of the rectifier stage.

In this embodiment, each said rectifier stage sector is referenced to a current vector I_refFrom two adjacent effective current vectors I_m、I_nThe resultant results are shown in fig. 3 and table-1 for two effective current vectors corresponding to each rectifier stage sector:

serial number	Rectifying stage sector	Effective current vector Im、In
			1	First sector	Iac、Iab
2	Second sector	Iac、Ibc
			3	Third sector	Ibc、Iba
4	The fourth sector	Iba、Ica
			5	The fifth sector	Ica、Icb
6	The sixth sector	Icb、Iab

TABLE-1

As will be appreciated by those skilled in the art, to prevent shorting of the Indirect Matrix Converter (IMC) inputs; therefore, the state of the switching tube of the IMC rectifying stage needs to satisfy the following formula:

namely: as shown in fig. 2, an Indirect Matrix Converter (IMC) rectification stage has three phases a, b, c, each phase having an upper leg p and a lower leg n; each bridge arm is provided with a bidirectional switch, 6 bidirectional switches and 12 switching tubes in total; wherein S is_ax、S_bx、S_cxThe switching state of the switching tube of the rectifier stage is represented when x is p, and the switching state of the upper bridge arm of the rectifier stage is represented when x is n, for the convenience of analysis, the switching tube is defined to be connected as 1 and disconnected as 0, and the formula represents that only one switching tube can be connected between the upper bridge arm and the lower bridge arm of the rectifier stage; an Indirect Matrix Converter (IMC) rectification stage thus has 9 switching states, i.e. S_ab、S_ac、S_bc、S_ba、S_ca、S_cb、S_aa、S_bb、S_cc(ii) a The 9 switch states respectively correspond to 9 current vectors and respectively correspond to 6 effective current vectors I_ab、I_ac、I_bc、I_ba、I_ca、I_cbAnd 3 zero current vectorsQuantity I_aa、I_bb、I_cc. Because the rectifier stage does not allow short circuit, the upper and lower bridge arms of the rectifier stage of the Indirect Matrix Converter (IMC) are respectively provided with a switching tube for conduction; with S_abFor example, S_abThe condition that the a-phase upper bridge arm is conducted and the b-phase upper bridge arm and the c-phase upper bridge arm are not conducted is shown, and the b-phase lower bridge arm is conducted and the a-phase lower bridge arm and the c-phase lower bridge arm are not conducted.

S200: dividing the output voltage of the inverter stage into 6 inverter stage sectors through 6 effective voltage vectors, wherein the three-phase current direction of each inverter stage sector is not changed;

specifically, the inverter stage output voltage passes through 6 effective voltage vectors V₁-V₆Averagely dividing the data into 6 inverter stage sectors, namely a first inverter stage sector and a sixth inverter stage sector; meanwhile, for convenience of description, 6 effective voltage vectors V arranged in sequence are provided₁-V₆In (1), the effective voltage vector V₁、V₃、V₅Called odd effective voltage vector, and a vector V of effective voltages₂、V₄、V₆Referred to as the even effective voltage vector.

Specifically, the division principle of dividing the inverter stage output voltage into 6 inverter stage sectors through 6 effective voltage vectors is as follows: and ensuring that the three-phase current direction of each inverter stage sector is not changed.

In this embodiment, taking the output voltage of the inverter stage as shown in fig. 6 as an example, the output voltage of the inverter stage-pi/6 to pi/6 is taken as the first sector of the inverter stage, pi/6 to pi/2 is taken as the second sector of the inverter stage, pi/2 to 5 pi/6 is taken as the third sector of the inverter stage, 5 pi/6 to 7 pi/6 is taken as the fourth sector of the inverter stage, 7 pi/6 to 3 pi/2 is taken as the fifth sector of the inverter stage, and 3 pi/2 to 11 pi/6 is taken as the sixth sector of the inverter stage.

As will be appreciated by those skilled in the art, to prevent the output of an Indirect Matrix Converter (IMC) from opening; therefore, the state of the switching tube of the IMC inverter stage needs to satisfy the following formula:

as shown in figure 2 of the drawings, in which,an Indirect Matrix Converter (IMC) inverter stage has A, B, C three phases, each phase having an upper leg P and a lower leg N; each bridge arm is provided with 6 switching tubes; wherein S is_Py、S_NyRepresents the switching state of the switching tube of the inverter stage, and when y is A, represents S_PAIs the upper bridge arm switch state of A tube, S_NAThe switching state of a lower bridge arm of the tube A is set; when y is B, it represents S_PBThe upper bridge arm of the B tube is in a switching state S_NBThe switching state of a lower bridge arm of the tube B is set; when y is C, it represents S_PCIs the upper bridge arm switch state of the C tube, S_NCThe switching state of a lower bridge arm of the C tube is set; for convenience of analysis, the conduction of the switching tube is defined as 1, the turn-off of the switching tube is defined as 0, and the formula indicates that at least one switching tube is conducted in each phase of the inverter stage and only one switching tube is conducted; the Indirect Matrix Converter (IMC) inverter stage thus has 8 switching states, i.e. S₁₀₀、S₁₁₀、S₀₁₀、S₀₁₁、S₀₀₁、S₁₀₁、S₀₀₀、S₁₁₁(ii) a A, B, C of an Indirect Matrix Converter (IMC) inversion stage has one switching tube per phase conducting because the inversion stage does not allow an open circuit; with S₁₀₀For example, S₁₀₀And the inverter stage is shown that the A-phase upper bridge arm is conducted and the A-phase lower bridge arm is not conducted, the B-phase lower bridge arm and the C-phase lower bridge arm are conducted and the B-phase upper bridge arm and the C-phase upper bridge arm are not conducted. 8 switch states respectively correspond to 6 effective voltage vectors V₁、V₂、V₃、V₄、V₅、V₆And two zero voltage vectors V₀And V₇。

S300: respectively calculating the current reference current vector I_refThe magnitude of the common-mode voltage under the action of the effective current vector of the falling rectifying-stage sector and 6 effective voltage vectors;

the common-mode voltage calculation method of the effective current vector and the effective voltage vector comprises the following steps:

judging the switching states of a rectification stage and an inverter stage corresponding to the effective current vector and the effective voltage vector;

calculating the common mode voltage u according to the corresponding switch state and the formula (VI)_cm；

Wherein u is_aFor phase-a input phase voltage, u_bFor phase b input phase voltage, u_cA phase c input phase voltage; s_ap、S_bp、S_cpThe switching states of three-phase switching tubes of a bridge arm a, b and c on the rectifier stage are represented; s_an、S_bn、S_cnThe switching states of three-phase switching tubes of a lower bridge arm a, b and c of the rectifier stage are represented; s_PA、S_PB、S_PCRepresenting the switching state of a three-phase switching tube of an upper bridge arm A, B, C of the inverter stage; s_NA、S_NB、S_NCThe switching states of the three-phase switching tubes of the lower arm A, B, C of the inverter stage are shown.

In the present embodiment, the current reference current vector I is used_refFalling into the first sector of the rectifier stage, for example, the effective current vector I needs to be calculated separately_ac(or I)_ab) And 6 effective voltage vectors V₁-V₆The magnitude of the common mode voltage.

For the sake of understanding, with the effective current vector I_acAnd effective voltage vector V₁The description is given for the sake of example: from the above, the effective current vector I_acCorresponding to the switching state of the rectifier stage as S_abThe condition that the a-phase upper bridge arm is conducted and the b-phase upper bridge arm and the c-phase upper bridge arm are not conducted is shown, and the b-phase lower bridge arm is conducted and the a-phase lower bridge arm and the c-phase lower bridge arm are not conducted; effective voltage vector V₁Corresponding to the switching state of the inverter stage being S₁₀₀And the inverter stage is characterized in that an A-phase upper bridge arm is conducted and an A-phase lower bridge arm is not conducted, a B-phase lower bridge arm and a C-phase lower bridge arm are conducted and a B-phase upper bridge arm and a C-phase upper bridge arm are not conducted. Therefore, there are:

as shown in fig. 5, in the first sector,

effective current vectorQuantity I_acAnd effective voltage vector V₂-V₆The calculation process is the same as the above calculation method, and the specific calculation results are shown in table-2:

TABLE-2

S400: selecting 3 effective voltage vectors V corresponding to small common-mode voltage_α、V_β、V_γSynthesizing a reference output voltage vector V_ref；

For example: with the above-mentioned reference current vector I_refFalling into the first sector of the rectifier stage as an example, it can be seen from table-2 that the common mode voltage is smaller for the three effective vectors V_α、V_β、V_γRespectively as follows: v₁、V₃、V₅Then V will be₁、V₃、V₅Synthetic reference output voltage vector V_ref。

S500: according to the current reference output voltage vector V_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γAnd switching the sequence to minimize the common mode voltage corresponding to the equivalent voltage vector of the switching process in the dead time.

For the convenience of calculation by those skilled in the art, table-3 lists the common-mode voltage values of the effective current vectors and the effective voltage vectors of the sectors of different rectifier stages in this embodiment for reference.

TABLE-3

It can be seen from table-3 that, in the specific division manner of each sector of the rectifying stage and the inverter stage based on this embodiment, when the reference current vector I is used as the reference current vector_refWhen the voltage vector falls into the odd sectors (i.e. the first sector, the third sector and the fifth sector) of the rectifier stage_α、V_β、V_γThree odd effective voltage vectors (V) are selected₁、V₃、V₅) (ii) a When referring to the current vector I_refWhen the voltage vector falls into even sectors (namely, second sector, fourth sector and sixth sector of the rectification stage), the effective voltage vector V is_α、V_β、V_γThree even effective voltage vectors (V) are selected₂、V₄、V₆) (ii) a However, it should be noted that the specific division modes of the sectors in the rectification stage and the inversion stage are different, and the final result is also different, and the final result needs to be obtained by calculation in sequence according to the actual division condition.

Specifically, as shown in fig. 8, a reference current vector of a first sector of the rectifying stage and a reference output voltage vector of a first sector of the inverter stage are shown;

specifically, as shown in fig. 9, a reference current vector of the second sector of the rectification stage and a reference output voltage vector of the first sector of the inverter stage are illustrated;

according to the current reference output voltage vector V_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γThe method for switching the sequence specifically comprises the following steps:

s51: obtaining a current reference output voltage vector V_refThe three-phase current direction of the sector of the inverter stage is located;

for convenience of explaining the technical scheme of the application, the voltage vector V is output according to the current reference_refFor example, as shown in fig. 6, the first sector in the inverter stage has the following three-phase current directions: i.e. i_As>0；i_Bs<0；i_Cs<0。

S52: calculating an equivalent voltage vector in each switching subsequence, the switching subsequence being the effective voltage vector V_α、V_β、V_γThe switching sequence of two adjacent effective voltage vectors in the dead time;

specifically, the switching subsequence includes: v_α-V_β(or V)_β-V_α)、V_β-V_γ(or V)_γ-V_β)、V_γ-V_α(or V)_α-V_γ) (ii) a With effective voltage vector V_α、V_β、V_γAre each V₁、V₃、V₅For example, the switching subsequence is V₁-V₃(or V)₃-V₁)、V₃-V₅(or V)₅-V₃)、V₅-V₁(or V)₁-V₅)；

Specifically, the method for calculating the equivalent voltage vector of the switching subsequence comprises the following steps:

s 521: acquiring the corresponding switch states of two effective voltage vectors in the switching subsequence;

for example for switching the subsequence V₁-V₃，V₁The corresponding switch state is S₁₀₀The switching states of the A, B, C-phase three upper bridge arm switching tubes are 1, 0 and 0 in sequence; v₃The corresponding switch state is S₀₁₀Namely, the switching states of the A, B, C-phase three upper bridge arm switching tubes are 0, 1 and 0 in sequence;

s 522: calculating the on-off state of an equivalent voltage vector based on the three-phase current direction;

the method for calculating the switching state of the A, B, C three-phase switching tube corresponding to the equivalent voltage vector specifically comprises the following steps:

a: when the state of the switching tube is switched (from 0 to 1 or from 1 to 0):

judging that the current direction corresponding to the switch tube in the three-phase current is greater than 0, and then taking the state of the switch tube to be 0 after equivalence;

judging that the current direction corresponding to the switch tube in the three-phase current is less than 0, and then taking 1 as the state of the switch tube after equivalence;

b: when the state of the switching tube is not changed: after equivalence, the state of the switch tube takes the original value.

For convenience of explanation of the above principle, the three-phase current is taken as i_As>0；i_Bs<0；i_Cs<0; switching subsequence is V₁-V₃To explain, as shown in fig. 7:

V₁-V₃during switching, the phase A is switched from 0 to 1 due to i_As>0, so the equivalent A phase state takes 0;

V₁-V₃during switching, the B phase is switched from 0 to 1 due to i_Bs<0, so the B phase state after equivalence takes 1;

V₁-V₃in the switching process, the C tube is unchanged (from 0 to 0), so that the equivalent C phase takes the original value, namely 0;

the equivalent switch states are 0, 1 and 0 in sequence, namely S₀₁₀。

s 523: and obtaining an equivalent voltage vector corresponding to the equivalent switching state of the equivalent switching tube based on the switching state of the equivalent switching tube.

As can be seen from the above, S₀₁₀The corresponding equivalent voltage vector is V₃Thus V₁-V₃The equivalent voltage vector during switching is V₃；

It will be appreciated that, through the above steps s522-s524, it is possible to obtain:

V₃-V₁the equivalent voltage vector in the switching process is V₃；

V₃-V₅The equivalent voltage vector during switching is V₄；

V₅-V₃The equivalent voltage vector during switching is V₄；

V₅-V₁The equivalent voltage vector during switching is V₅；

V₁-V₅The equivalent voltage vector during switching is V₅；

S53: obtaining a current reference current vector I_refCalculating the effective current vector of the sector of the rectification stage, and calculating the equivalent common-mode voltage of the effective current vector and each equivalent voltage vector;

with the current reference current vector I_refIf the sector in the rectifying stage is the first sector of the rectifying stage, the effective current vector is I_ab(or I)_ac)；

Effective current vector I_abWith equivalent voltageVector is V₃Is an equivalent common mode voltage of

Effective current vector I_abWith an equivalent voltage vector of V₄An equivalent common mode voltage of

Effective current vector I_abWith an equivalent voltage vector of V₅Is an equivalent common mode voltage of

S54: obtaining a current reference current vector I_refMinimum input line voltage peak value of the sector of the rectification stage;

with the current reference current vector I_refIf the sector in the rectifying stage is the first sector in the rectifying stage, the minimum input line voltage peak value is

S55: selecting a switching subsequence corresponding to the minimum input line voltage peak value 1/3 and having a peak value in all equivalent common mode voltages to obtain the effective voltage vector V_α、V_β、V_γAnd switching the sequence.

The above equivalent voltage vector V₃、V₄、V₅The equivalent common mode voltage peak equal to the minimum input line voltage peak 1/3 is: v₃And V₅；

So that its corresponding switching sub-sequence is V₁-V₃(or V)₃-V₁) And V₅-V₁(or V)₁-V₅) (ii) a The switching sequence of the three final effective voltage vectors thus obtained is: v₅-V₁-V₃-V₁-V₅。

For the convenience of calculation and understanding of those skilled in the art, as shown in table-3, the common mode voltage values in different three-phase current directions, different effective voltage vectors, and different switching sequences corresponding to the different effective voltage vectors are represented in a form of preserving a decimal number according to the division example based on the corresponding sector of the present embodiment.

TABLE-4

For the convenience of implementation and understanding of those skilled in the art, table-3 shows the final effective voltage vector V corresponding to the sectors of different rectification stages with the input current vector falling into the sectors of different rectification stages and the output voltage vector falling into the sectors of different inversion stages based on the division example of the corresponding sectors in the present implementation_α、V_β、V_γAnd switching the sequence.

TABLE-5

According to the steps, the common-mode voltage peak value corresponding to the equivalent voltage vector in the switching process in the dead time can be minimized based on the switching sequence, and the common-mode voltage peak value caused by the dead time effect is eliminated.

The working principle is as follows: the current reference current vector I is respectively calculated by dividing the input voltage of the rectifier stage into 6 rectifier stage sectors according to the phase angle, dividing the output voltage of the inverter stage into 6 inverter stage sectors through 6 effective voltage vectors_refThe effective current vector of the falling rectifier stage sector and the common-mode voltage under the action of 6 effective voltage vectors, andselecting 3 effective voltage vectors V corresponding to small common-mode voltage_α、V_β、V_γSynthesizing a reference output voltage vector V_refSo that the common mode voltage peak can be suppressed to 0.29V_in；

Because the three-phase current directions of each sector of the IMC inverter stage are different, when the effective voltage vector switching of the inverter stage needs two switching tubes to act simultaneously, other vectors are inevitably introduced due to the action of a freewheeling diode in dead time, so that the common-mode voltage peak value of the inverter stage is changed, namely the dead time effect. The common mode voltage spike caused by the dead zone effect may seriously affect the peak suppression effect of the common mode voltage. By outputting a voltage vector V in accordance with the present reference_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γThe switching sequence and the common mode voltage peak value corresponding to the equivalent voltage vector in the switching process in the dead time are minimum, so that the common mode voltage peak caused by the dead time effect can be eliminated, and the common mode voltage of the indirect matrix converter is restrained by 71%.

In a preferred embodiment, two adjacent effective current vectors I_m、I_nSynthesizing the reference current vector I by a formula (I) and a formula (II)_ref：

I_ref＝(d_{α_m}+d_{β_m}+d_{γ_m})I_m+(d_{α_n}+d_{β_n}+d_{γ_n})I_n(one);

wherein d is_αIs an effective voltage vector V_αDuty cycle of (d); d_βIs an effective voltage vector V_βDuty cycle of (d); d_γIs an effective voltage vector V_γDuty cycle of (d); d_mAs the effective current vector I_mDuty cycle of (d); d_nAs the effective current vector I_nThe duty cycle of (c).

In particular，d_{α_m}、d_{β_m}、d_{γ_m}、d_{α_n}、d_{β_n}、d_{γ_n}For the intermediate quantity of the calculation, the product of the two duty cycles is expressed without specific meaning.

In a preferred embodiment, d is calculated according to formula (three) or formula (four)_α、d_β、d_γ、d_m、d_nThe value of (c):

wherein, theta₁Is I_refAnd I_mThe included angle of (A); theta.theta.₂Is a V_refAnd V_αAngle u of_DCIs the average value, u, of the DC bus voltage of one carrier cycle_{DC_m}And u_{DC_n}Are respectively d_mAnd d_nThe dc bus voltage when active.

Wherein, the formula (iv) can be specifically expressed as:

in a preferred embodiment, the reference output voltage vector V is synthesized according to the formula (V)_ref：

In a preferred embodiment, the 6 active voltage vectors comprise 3 odd active voltage vectors V₁、V₃、V₅And 3 even effective voltage vectors V₂、V₄、V₆；

The included angle between two adjacent effective voltage vectors is 60 degrees, and the odd effective voltage vectors and the even effective voltage vectors are arranged at intervals;

two adjacent effective current vectors I_m、I_nIs 60 degrees.

In a preferred embodiment, the method further comprises the following steps:

according to the effective current vector I of the current input voltage in the rectifying stage sector_m、I_nControlling a switching state of the IMC rectification stage;

controlling a switching state of the IMC inverter stage to adjust the effective voltage vector V_α、V_β、V_γAnd switching the sequence.

Example 2

On the basis of embodiment 1, in this embodiment, in order to further verify the common mode rejection effect, the input-output voltage quality characteristic, and the elimination of the dead zone effect common mode voltage spike of the IMC under the modulation method of the present invention, the following experimental platform is established herein;

wherein d in formula (III) is ensured_α、d_β、d_γGreater than zero and not greater than 1, thus setting the maximum value of the voltage transfer ratio m to 0.5;

the input power factor is set to 1, and the experiment of the conventional method and the common mode peak suppression method of the robot servo driver IMC proposed in the present application is performed when m is 0.2 and m is 0.4, respectively, and the experimental parameters are shown in table-6:

TABLE-6

Fig. 10 and 11 are experimental results of the conventional SVM method and the common mode voltage suppression method of the present invention, respectively, in which the voltage transfer ratio m is 0.2. Common mode voltage u from top to bottom_cmPeak value u of dc bus voltage_dcPhase A output current i_AA phase input current i_a；

Fig. 10 shows that when the voltage transfer ratio is 0.2, the common mode voltage peak of the conventional SVM method is 120V, which is higher than the input voltage peak of 100V, because the switching peak is caused by the on and off of the device, and the size of the switching peak is mainly affected by the switching parameters and the parasitic inductance of the circuit, in this experiment, the switching peak is about 15-25V because it is not an ideal switch, and the switching peak is inevitably generated;

fig. 11 shows that when the voltage transfer ratio is 0.2, the common mode peak suppression method for the robot servo driver IMC provided by the present application includes observing the common mode voltage in an amplification manner, where the common mode voltage peak is about 30V without considering the switching peak caused by switching on and off, and the common mode voltage peak caused by a dead zone effect does not appear, and if the switching peak caused by switching on and off is not considered, the experimental result is consistent with the analysis.

Fig. 12 and 13 are experimental results of a conventional SVM method having a voltage transfer ratio m of 0.4 and a common mode peak suppression method of the robot servo driver IMC provided in the present application, respectively. Experiments prove that the common-mode suppression method of the invention integrally suppresses the common-mode voltage of the IMC, and the input and output currents of the common-mode suppression method still keep sine.

In summary, when the voltage transfer ratio is m is 0.2 and m is 0.4, it can be seen through experiments that the common mode peak suppression method of the robot servo driver IMC of the present invention is compared with the conventional SVM method, that the common mode voltage in the common mode peak suppression method of the robot servo driver IMC of the present application is reduced by 71% compared with the conventional method, which is reduced to about 29% of the original value, and the common mode voltage peak caused by the dead zone effect does not occur. Compared with the traditional SVM modulation method, the common mode voltage peak value is reduced, and meanwhile the input and output performance of the common mode suppression method is not reduced.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims (6)

1. A common-mode peak suppression method of a robot servo driver IMC is characterized by comprising the following steps:

dividing the input voltage of the rectifier stage into 6 rectifier stage sectors according to phase angles; each said rectifier stage sector including a maximum input phase voltage peak, a minimum input phase voltage peak, a maximum input line voltage peak, and a minimum input line voltage peak; within each said rectifier stage sector, a reference current vector I_refFrom two adjacent effective current vectors I_m、I_nSynthesizing to obtain;

dividing the output voltage of the inverter stage into 6 inverter stage sectors through 6 effective voltage vectors, wherein the three-phase current direction of each inverter stage sector is not changed;

respectively calculating the current reference current vector I_refThe magnitude of the common-mode voltage under the action of the effective current vector of the falling rectifying-stage sector and 6 effective voltage vectors;

selecting 3 effective voltage vectors V corresponding to small common-mode voltage_α、V_β、V_γSynthesizing a reference output voltage vector V_ref；

According to the current reference output voltage vector V_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γSwitching order to minimize the common mode voltage corresponding to the equivalent voltage vector of the switching process in the dead time;

according to the current reference output voltage vector V_refAdjusting the three-phase current direction of the sector of the inverter stage to adjust the effective voltage vector V_α、V_β、V_γThe method for switching the sequence specifically comprises the following steps:

obtaining a current reference output voltage vector V_refThe three-phase current direction of the sector of the inverter stage is located;

acquiring the corresponding switch states of two effective voltage vectors in each switching subsequence, calculating the switch state of an equivalent voltage vector based on the three-phase current direction, and acquiring the equivalent voltage vector corresponding to the equivalent voltage vector based on the switch state of an equivalent switching tube; the switching subsequence is the effective voltage vector V_α、V_β、V_γThe switching sequence of two adjacent effective voltage vectors in the dead time;

obtaining a current reference current vector I_refCalculating the effective current vector of the sector of the rectification stage, and calculating the equivalent common-mode voltage of the effective current vector and each equivalent voltage vector;

obtaining a current reference current vector I_refMinimum input line voltage peak value of the sector of the rectification stage;

selecting a switching subsequence corresponding to the minimum input line voltage peak value 1/3 in all equivalent common mode voltage peak values to obtain the effective voltage vector V_α、V_β、V_γAnd switching the sequence.

2. The method of claim 1, wherein two adjacent effective current vectors I are used for common mode peak rejection of the IMC_m、I_nSynthesizing the reference current vector I by a formula (I) and a formula (II)_ref：

I_ref＝(d_{α_m}+d_{β_m}+d_{γ_m})I_m+(d_{α_n}+d_{β_n}+d_{γ_n})I_n(one);

wherein d is_αIs an effective voltage vector V_αDuty cycle of (d); d_βIs an effective voltage vector V_βDuty cycle of (d); d_γIs an effective voltage vector V_γDuty cycle of (d); d_mAs the effective current vector I_mDuty cycle of (d); d_nIs provided withEffective current vector I_nThe duty cycle of (c).

3. The method of claim 2, wherein d is calculated according to formula (three) or formula (four)_α、d_β、d_γ、d_m、d_nThe value of (c):

wherein, theta₁Is I_refAnd I_mThe included angle of (A); theta₂Is a V_refAnd V_αThe included angle of (A); u. of_DCThe average value of the direct current bus voltage in one carrier period is obtained; u. of_{DC_m}And u_{DC_n}Are respectively d_mAnd d_nThe dc bus voltage when active.

4. The method of claim 3, wherein the reference output voltage vector V is synthesized according to equation (V)_ref：

V_ref＝(d_{α_m}+d_{α_n})V_α+(d_{β_m}+d_{β_n})V_β+(d_{γ_m}+d_{γ_n})V_γ(V).

5. The method of claim 1, wherein the method of common mode peak rejection of the IMC,

the 6 effective voltage vectors comprise 3 odd effective voltage vectors and 3 even effective voltage vectors;

the included angle between two adjacent effective voltage vectors is 60 degrees, and the odd effective voltage vectors and the even effective voltage vectors are arranged at intervals;

two adjacent effective current vectors I_m、I_nIs 60 degrees.

6. The method of claim 1, further comprising the steps of:

according to the effective current vector I corresponding to the current input voltage in the rectifying stage sector_m、I_nControlling a switching state of the IMC rectification stage;

controlling a switching state of the IMC inverter stage to adjust the effective voltage vector V_α、V_β、V_γAnd switching the sequence.

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